$\dfrac{4}{6} - \dfrac{4}{3} = {?}$
$ = {\dfrac{4 \times 1}{6 \times 1}} - {\dfrac{4 \times 2}{3 \times 2}} $ $ = {\dfrac{4}{6}} - {\dfrac{8}{6}} $ $ = \dfrac{{4} - {8}}{6} $ $ = -\dfrac{4}{6}$